In a house, various heat sources might be installed such as electrical heaters, water based heating systems, HVAC systems etc. These heat sources are characterised by their dissimilarity in influencing the indoor climate and the costs of use. The indoor climate is defined by a huge number of variables such as an average temperature level, the temperature distribution, i.e. local variations of the temperature from the average temperature, draught, humidity, CO2 level, light intensity etc. However, not all combinations of these variables are perceived as being equally comfortable.
By combining the heat transmission from a number of different heat sources, various comfort determinative variables can be influenced and controlled actively. Hence, a more comfortable indoor climate can be obtained. As an example, a heat source located under a window will be suitable for removing the cold draught caused by the cold window whereas it inconsiderably contributes to the temperature of the floor. A floor heating system, on the other hand, contributes very little to the removal of cold draught, and the time constant or inertia of the floor heating system renders floor heating completely unsuitable for compensation of a sudden climatic fluctuation. An electrically operated heating device comprising a heated surface with a ventilator for forced convection may very rapidly decrease the relative humidity by raising the temperature swiftly. In addition to the differences in the influence of the climate, different costs may be associated with the different heat sources. As an example, it is in many countries more expensive to use an electrical heater than a water based heating system (e.g. with an oil-fired boiler).
In a similar manner, various ways of cooling an environment may be combined in order to increase the comfort of the environment. As an example, the temperature of an environment can be lowered by a compressor-based cooling system. Such a system may provide a swift change in temperature even with relatively warm outdoor conditions. The temperature could be reduced by ventilation (requiring lower outdoor temperatures than indoor temperatures), and the temperature could be lowered by thermal convection e.g. with a ground heating/cooling system. Naturally, the costs of the temperature reduction and other comfort determinative variables than the temperature may be influenced by the selection of the source of cooling, e.g. the humidity, and draught.